The present invention relates to yarn carrier tubes supporting packages of yarn wound thereon. More particularly, the present invention relates to a yarn carrier tube having a start-up groove for receiving and capturing a yarn tail.
Carrier tubes provide support for packages of yarn or other textile fibers. The support provided by the carrier tube facilitates handling of the yarn during processing operations such as yarn dyeing, for example. The yarn is received onto the carrier tube in a high-speed winding operation to form a yarn package on the tube.
To facilitate engagement with yarn to be wound, known yarn carrier tubes include a circumferential start-up groove formed adjacent an end of the tube. The start-up groove receives and retains a tail-end portion of the yarn. It is known to include an angled sidewall in the start-up groove to define a substantially V-shaped cross-section. Pinching of the yarn tail in the narrowed portions of the V-shaped groove facilitates capture of the yarn.
According to the present invention, a suction system for a yarn carrier tube is provided for drawing a yarn tail into a start-up groove during rotation of the carrier tube. The suction system includes air-scoop openings extending between interior and exterior surfaces of the tube. Each of the air-scoop openings includes a leading surface and a trailing surface on opposite sides of the opening with respect to a circumferential direction of tube rotation. At least a portion of the trailing surface is obliquely oriented with respect to an adjacent portion of either the interior or exterior surface of the tube such that air is moved through the air-scoop opening during rotation of the tube. The leading and trailing surfaces of each of the air-scoop openings converge towards each other to form a narrowed portion of the opening in which pressure in the moving air is reduced. The yarn tail drawing system also includes a plurality of passages each having opposite ends respectively communicating with the start-up groove and with the narrowed portion of one of the air-scoop openings to connect the start-up groove with the reduced pressure of the air-scoop opening.
According to a preferred embodiment of the invention, the start-up groove includes a first sidewall oriented substantially radially with respect to the tube and a second sidewall oriented obliquely with respect to the first sidewall to define a V-shaped cross-section. Each of the passageways of the yarn tail drawing system is connected to the first sidewall of the start-up groove and extends parallel to the second sidewall. In an alternative embodiment, the passageways include a first portion connected to the second sidewall of the groove and extending parallel to the first sidewall and a second portion connected to the first portion and extending perpendicular thereto.
According to a preferred embodiment of the invention, the trailing surface of each of the air-scoop openings is substantially planar and an outer portion of the leading surface is curved to define with the trailing surface the narrowed portion of the opening.